title: Distinct functions of calmodulin are required for the uptake step of receptor-mediated endocytosis in yeast: the type I myosin Myo5p is one of the calmodulin targets.
abstract: The uptake step of receptor-mediated endocytosis in yeast is dependent on the calcium binding protein calmodulin (Cmd1p). In order to understand the role that Cmd1p plays, a search was carried out for possible targets among the genes required for the internalization process. Co-immunoprecipitation, two-hybrid and overlay assays demonstrated that Cmd1p interacts with Myo5p, a type I unconventional myosin. Analysis of the endocytic phenotype and the Cmd1p-Myo5p interaction in thermosensitive cmd1 mutants indicated that the Cmd1p-Myo5p interaction is required for endocytosis in vivo. However, the Cmd1p-Myo5p interaction requirement was partially overcome by deleting the calmodulin binding sites (IQ motifs) from Myo5p, suggesting that these motifs inhibit Myo5p function. Additionally, genetic and biochemical evidence obtained with a collection of cmd1 mutant alleles strongly suggests that Cmd1p plays an additional role in the internalization step of receptor-mediated endocytosis in yeast.
authors.affiliation: Biozentrum of the University of Basel, CH-4056 Basel, Switzerland.
authors.forename: M I
authors.initials: MI
authors.lastname: Geli
authors.forename: A
authors.initials: A
authors.lastname: Wesp
authors.forename: H
authors.initials: H
authors.lastname: Riezman
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics / Q000502:physiology; D002147:Calmodulin / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology*; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D017353:Gene Deletion; D024461:Myosin Type I; D009218:Myosins / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: D002147:Calmodulin; D005656:Fungal Proteins; C100412:MYO5 protein, S cerevisiae; D011956:Receptors, Cell Surface; D029701:Saccharomyces cerevisiae Proteins; D024461:Myosin Type I; D009218:Myosins